The present invention is directed to a light waveguide plug device which has two halves with one of the halves being a body provided with a concentric bore for receiving a light waveguide with the end of the light waveguide lying in the plane of the end face of the body and the body being adjustably received in the other half of the plug device which carries a light-emitting surface so that the end of the light waveguide is in the desired position for receiving light from the light-emitting surface.
A light waveguide plug device is disclosed in German Gebrauchmuster No. 37 76 066. This device has a guide sleeve which has a bore that extends axially therethrough. A pin-like body having a concentric bore containing a light waveguide is inserted from one end of the guide sleeve and a housing of an LED can be inserted in the other end of the guide sleeve. With suitable dimensioning of these various parts, a desired adjustment of the end face of the light waveguide to the optical active region or surface of the LED can be obtained so that the light emitted by the LED is beamed into the light waveguide with a high efficiency.
Given such a light waveguide plug device which is provided for the connection of an optical transmitter to the light waveguide, it is desirable to monitor the intensity of the radiation emitted by the LED in order, for example, to be able to trigger an alarm when the radiated power or intensity drops below a predescribed value.